Methods and systems for providing access control to secured data

ABSTRACT

In a system for providing access control management to electronic data, techniques to secure the electronic data and keep the electronic data secured at all times are disclosed. According to one embodiment, a secured file or secured document includes two parts: an attachment, referred to as a header, and an encrypted document or data portion. The header includes security information that points to or includes the access rules and a file key. The access rules facilitate restrictive access to the secured document and essentially determine who/when/how/where the secured document can be accessed. The file key is used to encrypt/decrypt the encrypted data portion. Only those who have the proper access privileges are permitted to retrieve the file key to encrypt/decrypt the encrypted data portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is continuation of U.S. application Ser. No.15/402,883, filed Jan. 10, 2017, which is a continuation of U.S.application Ser. No. 14/034,147 (now U.S. Pat. No. 9,542,560), filedSep. 23, 2013, which is a divisional of U.S. application Ser. No.12/057,015, filed Mar. 27, 2008 (now U.S. Pat. No. 8,543,827), which isa continuation of U.S. application Ser. No. 10/074,804, filed Feb. 12,2002 (now U.S. Pat. No. 7,380,120), which claims the benefit of U. S.Provisional Application No. 60/339,634, filed Dec. 12, 2001, andentitled “Pervasive Security Systems,” which are hereby incorporated byreference in their entireties.

This application is related to U.S. application Ser. No. 10/259,078filed Sep. 9, 2002 (now abandoned), Ser. No. 10/259,075 filed Sep. 9,2002 (now abandoned), Ser. No. 10/325,102 filed Dec. 20, 2002 (nowabandoned), Ser. No. 10/405,587 filed Apr. 1, 2003 (now abandoned), Ser.No. 10/206,737 filed Jul. 26, 2002 (now abandoned), and Ser. No.10/159,537 filed May 31, 2002 (now U.S. Pat. No. 7,178,033), which areall incorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to the area of protecting data in anenterprise environment, and more particularly, relates processes,systems, architectures, and software products for providing pervasivesecurity to digital assets at all times.

Background Art

The Internet is the fastest growing telecommunications medium inhistory. This growth and the easy access it affords have significantlyenhanced the opportunity to use advanced information technology for boththe public and private sectors. It provides unprecedented opportunitiesfor interaction and data sharing among businesses and individuals.However, the advantages provided by the Internet come with asignificantly greater element of risk to the confidentiality andintegrity of information. The Internet is a widely open, public, andinternational network of interconnected computers and electronicdevices. Without proper security means, an unauthorized person ormachine may intercept any information traveling across the Internet andeven get access to proprietary information stored in computers thatinterconnect to the Internet, but are otherwise generally inaccessibleby the public.

There are many efforts in progress aimed at protecting proprietaryinformation traveling across the Internet and controlling access tocomputers carrying the proprietary information. Cryptography allowspeople to carry over the confidence found in the physical world to theelectronic world, thus allowing people to do business electronicallywithout worries of deceit and deception. Every day hundreds of thousandsof people interact electronically, whether it is through e-mail,e-commerce (business conducted over the Internet), ATM machines, orcellular phones. The perpetual increase of information transmittedelectronically has lead to an increased reliance on cryptography.

One of the ongoing efforts in protecting the proprietary informationtraveling across the Internet is to use one or more cryptographictechniques to secure a private communication session between twocommunicating computers on the Internet. The cryptographic techniquesprovide a way to transmit information across an insecure communicationchannel without disclosing the contents of the information to anyoneeavesdropping on the communication channel. Using an encryption processin a cryptographic technique, one party can protect the contents of thedata in transit from access by an unauthorized third party, yet theintended party can read the data using a corresponding decryptionprocess.

A firewall is another security measure that protects the resources of aprivate network from users of other networks. However, it has beenreported that many unauthorized accesses to proprietary informationoccur from the inside, as opposed to from the outside. An example ofsomeone gaining unauthorized access from the inside is when restrictedor proprietary information is accessed by someone within an organizationwho is not supposed to do so. Due to the open nature of the Internet,contractual information, customer data, executive communications,product specifications, and a host of other confidential and proprietaryintellectual property remains available and vulnerable to improperaccess and usage by unauthorized users within or outside a supposedlyprotected perimeter.

A governmental report from General Accounting Office (GAO) details“significant and pervasive computer security weaknesses at sevenorganizations within the U.S. Department of Commerce, the widespreadcomputer security weaknesses throughout the organizations have seriouslyjeopardized the integrity of some of the agency's most sensitivesystems.” Further it states: “Using readily available software andcommon techniques, we demonstrated the ability to penetrate sensitiveCommerce systems from both inside Commerce and remotely, such as throughthe Internet,” and “Individuals, both within and outside Commerce, couldgain unauthorized access to these systems and read, copy, modify, anddelete sensitive economic, financial, personnel, and confidentialbusiness data . . . .” The report further concludes “[i]ntruders coulddisrupt the operations of systems that are critical to the mission ofthe department.”

In fact, many businesses and organizations have been looking foreffective ways to protect their proprietary information. Typically,businesses and organizations have deployed firewalls, Virtual PrivateNetworks (VPNs), and Intrusion Detection Systems (IDS) to provideprotection. Unfortunately, these various security means have been proveninsufficient to reliably protect proprietary information residing onprivate networks. For example, depending on passwords to accesssensitive documents from within often causes security breaches when thepassword of a few characters long is leaked or detected. Therefore,there is a need to provide more effective ways to secure and protectdigital assets at all times.

BRIEF SUMMARY OF THE INVENTION

This section is for the purpose of summarizing some aspects of thepresent invention and to briefly introduce some preferred embodiments.Simplifications or omissions may be made to avoid obscuring the purposeof the section. Such simplifications or omissions are not intended tolimit the scope of the present invention.

The present invention is related to processes, systems, architecturesand software products for providing pervasive security to digital assetsat all times and is particularly suitable in an enterprise environment.In general, pervasive security means that digital assets are secured atall times and can only be accessed by authenticated users withappropriate access rights or privileges, wherein the digital assets mayinclude, but not be limited to, various types of documents, multimediafiles, data, executable code, images and texts.

In one aspect of the present invention, a server module executable in aserver computer is configured to provide access control (AC) managementfor a group of users, software agents, or devices with a need to accesssecured documents under the access control management. Within the servermodule, various access rules for the secured documents and/or accessprivileges for the users or software agents can be created, updated, andmanaged so that the users, software agents, or devices with the properaccess privileges can access the secured documents if granted by thecorresponding access rules in the secured documents. According to oneembodiment, a secured document includes a header and encrypted dataportion. The header includes encrypted security information to controlthe access to the encrypted data portion. A user key associated with anauthenticated user must be retrieved in order to decrypt the encryptedsecurity information. Once the security information becomes available,the access rules are retrieved from the security information and can bemeasured against the access privileges of the user who is accessing thesecured document. If such measurement succeeds, a file key is retrievedfrom the security information and used to decrypt the encrypted dataportion, subsequently, a clear version of the secured document is madeavailable to the user.

In another aspect of the present invention, the AC management isperformed in a distributed fashion. A number of local server computersare employed to operate largely on behalf of a central serverresponsible for the centralized AC management. Such a distributedfashion ensures the dependability, reliability, and scalability of theAC management undertaking by the central server. According to oneembodiment, a cache version of the server module is loaded and executedin a local server. As a result, it is not necessary for a client machineto have live consultation with the central server when accessing secureddocuments. In fact, the secured documents can still be accessed even ifthe central server is down or a connection thereto is not available.

In still another aspect of the present invention, the local version fora local server can be dynamically reconfigured depending on a user'scurrent location. According to one embodiment, a local version for alocal server is so configured that it only services the users, softwareagents, or devices that are local to the local server or have previouslybeen authenticated by the local server. When a user moves from onelocation to another location, upon detecting a new location of the userwho has moved from a previous location, a local version for the newlocation is reconfigured to add support for the user while at the sametime a local version for the previous location is reconfigured to removesupport for the user. As a result, the security is enhanced while the ACmanagement can be efficiently carried out to ensure that only one accessfrom the user is permitted at any time across an entire organization,regardless of how many locations the organization has or what accessprivileges the user may be granted.

In still yet another aspect of the present invention, the format of thesecured document is so designed that the security information of adocument stays with the document being secured at all times. As such,this integrated mechanism facilities the transportation of secureddocuments to other locations without the loss of the securityinformation therein and/or creating difficulty of accessing the secureddocuments from the other locations. According to one embodiment, asecured file or secured document includes two parts: an attachment,referred to as a header, and an encrypted document or data portion. Theheader includes security information that points to or includes theaccess rules and a file key. The access rules facilitate restrictiveaccess to the secured document and essentially determinewho/when/how/where the secured document can be accessed. The file key isused to encrypt/decrypt the encrypted data portion. Only those who havethe proper access privileges are permitted to retrieve the file key toencrypt/decrypt the encrypted data portion. Depending on an exactimplementation, the header may include other information (e.g., a flag,a signature, or version number) to facilitate the detection of thesecurity nature of the document. Alternatively, the two parts, encryptedsecurity information and the encrypted data portion, may be encryptedagain to be a secured file or secured document.

In still yet another aspect of the present invention, a client moduleexecutable in a client machine is configured to provide access controlto the secured documents that may be located in a local store, anothercomputer machine or somewhere over a data network. According to oneembodiment, the client module includes a document-securing module thatis implemented to operate in an operating system. In particular, thedocument-securing module operates in a path through which a documentbeing accessed would pass, as such, the document can be examined ordetected for the security nature. If the document is secured, thedocument-securing module obtains a user or group key to decrypt thesecurity information in the header thereof for the access rules. If auser accessing the document is determined to have the access privilegeto the secured document, a file key is retrieved from the securityinformation and a cipher module is activated to decrypt the encrypteddata portion with the file key. Likewise, if a document is to besecured, the cipher module encrypts clear data from the document tocreate the encrypted data portion. The document-securing moduleintegrates proper or desired security information with the encrypteddata portion to produce the secured document. As the document securingmodule operates in an operating system, the en/decryption process istransparent to the user.

In still yet another aspect of the present invention, a client module ina client machine activates an off-line access module to provide anoff-line access mechanism for those users on the go. When a user decidesto be away from a network premises or on a business trip, an off-lineaccess request may be generated by an off-line access module in theclient machine and forwarded to an AC server. In response, the AC servermay grant the off-line access request to the user as well as the clientmachine from which the user will access secured documents off-line.According to one embodiment, the AC server may provide amended ortentative access rules, access privileges or a user key that willautomatically expire when a predetermined time ends or become invalidthe next time the client machine is connected to the AC server. As aresult, the user can access some or all the secured documents in theclient machine and, at the same time, create secured documents, allaccessed or secured with the tentative access rules, access privilegesor the user key. During the off-line access period, an access reportmanager may be activated to record all activities of the user accessingthe secured documents. When the client machine is once again connectedto the AC server, the access activities of the secured documents can bereported to the AC server to facilitate the access control managementand synchronization of the secured documents accessed or createdoff-line.

One of the objects in the present invention is to provide a genericsecuring mechanism that can protect secured digital assets at all times.

Other objects, features, and advantages of the present invention willbecome apparent upon examining the following detailed description of anembodiment thereof, taken in conjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1A shows a basic system configuration in which the presentinvention may be practiced in accordance with a preferred embodimentthereof;

FIG. 1B shows a configuration in which a central server and localservers are employed;

FIG. 1C shows a configuration suitable for a small group of users withno local servers employed;

FIG. 1D shows internal construction blocks of a computing device (e.g.,a client machine, a central server and a local server) in which thepresent invention may be implemented and executed;

FIG. 2A is an illustration diagram of securing a created document;

FIG. 2B illustrates an exemplary structure of a secured documentincluding a header and an encrypted data portion;

FIG. 2C.1 illustrates another exemplary structure of a secured documentincluding multiple users' information in a header and an encryptedportion;

FIG. 2C.2 illustrates still another exemplary structure of a secureddocument including security blocks in a header and an encrypted portion;

FIG. 2C.3 shows an exemplary header in a markup language correspondingto that of the secured document structure illustrated in FIG. 2C.2;

FIG. 2D shows an exemplary graphic user interface (GUI) that can be usedto establish or create the access rules by users;

FIG. 2E shows a directory structure including a clear folder and secured(active) folders, wherein the clear folder is generally for storingsystem files or

files that are not intended for protection and the secured folders arefor data files and documents in secured form;

FIG. 3 shows an exemplary implementation 300 of how a document securingmodule (DSM) 302 interacting with and operating within an operatingsystem 304 (e.g., Windows 2000®) to ensure that a document is madesecure in a manner that is transparent to the user;

FIG. 4A shows a flowchart of the process of securing a document beingcreated according to one embodiment of the present invention;

FIG. 4B shows a flowchart of an exemplary process of receiving theaccess rules and may be incorporated into the process of FIG. 4A tofacilitate the process of securing a document;

FIG. 4C shows a flowchart of a process of accessing a secured documentaccording to one embodiment, and shall be understood in conjunction withFIG. 3;

FIG. 5A shows a function block diagram of a (access control) serverdevice in which a server module resides in a memory space and isexecutable by one or more processors in the server device;

FIG. 5B.1 and FIG. 5B.2 illustrate, respectively, two structures, oneshowing exemplary access privileges for the users and the other showingwhat may be in a user key manager according to one embodiment of thepresent invention;

FIG. 5B.3 shows a flowchart of updating a user key process;

FIG. 5B.4 shows a flowchart of a server-assisted process of accessingsecured documents according to one embodiment, and shall be understoodin conjunction with FIG. 3;

FIG. 5B.5 shows a flowchart of a server assisted process of securing adocument according to one embodiment, and shall also be understood inconjunction with FIG. 3.

FIG. 5C shows a functional block diagram of a local server device which,in many ways, is similar to that of the server as illustrated in FIG.5A;

FIG. 5D shows a table of all the users with different access privilege,the table being managed by a central server;

FIG. 5E shows respective tables, each accessed by a local server, as aresult, users need only to check with a corresponding local server; nonewould be affected if other local servers are down for whatever reasonsor are disconnected from the central server;

FIG. 5F illustrates the accessibility for each of the users, instead ofhaving three identical cache modules, each permitting John to accessfrom any of the three locations, only one cache module is configured topermit John to access form one of the three locations at one time;

FIG. 5G shows a dynamic caching access control management by adding Johnto another cache module that now can service John moved from anotherlocation;

FIG. 5H and FIG. 5I show respectively the changing accessibility foruser as a result of the dynamic caching access control management;

FIG. 6A shows a flowchart of a user authentication process that may beimplemented in a central server or a local server;

FIG. 6B shows a flowchart of dynamically configuring the access controlmanagement process which may be implemented in one or more local serversin conjunction with a central server;

FIG. 6C shows a flowchart of reconfiguring the local modules' process,according to one embodiment, and may be used in FIG. 6B;

FIG. 7A shows a functional block diagram of a client machine that may beused to practice the present invention;

FIG. 7B shows a flowchart of providing off-line access processing inaccordance with one embodiment of the present invention; and

FIG. 7C illustrates an amendment of the access rules placed into asecured document that can be accessed by Users, A, B, C and D, whereinUser A has requested off-line access and has been granted the request,while Users B, C and D cannot access the secured documents off-line.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is related to processes, systems, architectures,and software products for providing pervasive security to digital assetsat all times. In general, pervasive security means that digital assetsare secured at all times and can only be accessed by authenticated userswith appropriate access privileges. The present invention isparticularly suitable in an enterprise environment.

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention.However, it will become obvious to those skilled in the art that thepresent invention may be practiced without these specific details. Thedescription and representation herein are the common means used by thoseexperienced or skilled in the art to most effectively convey thesubstance of their work to others skilled in the art. In otherinstances, well-known methods, procedures, components, and circuitryhave not been described in detail to avoid unnecessarily obscuringaspects of the present invention.

Reference herein to “one embodiment” or “an embodiment” means that aparticular feature, structure, or characteristic described in connectionwith the embodiment can be included in at least one embodiment of theinvention. The appearances of the phrase “in one embodiment” in variousplaces in the specification are not necessarily all referring to thesame embodiment, nor are separate or alternative embodiments mutuallyexclusive of other embodiments. Further, the order of blocks in processflowcharts or diagrams representing one or more embodiments of theinvention do not inherently indicate any particular order nor imply anylimitations in the invention.

To facilitate the description of the present invention, it deemsnecessary to provide definitions for some terms that will be usedthroughout the disclosure herein. It should be noted that thedefinitions following are to facilitate the understanding and describethe present invention according to an embodiment. The definitions mayappear to include some limitations with respect to the embodiment, theactual meaning of the terms has applicability well beyond suchembodiment, which can be appreciated by those skilled in the art:

Digital Asset—defines a type of electronic data that includes, but isnot limited to, various types of documents, multimedia files, streamingdata, dynamic or static data, executable code, images, and texts.

File or document—interchangeably used herein, indicates one type ofdigital asset and generally is in a clear mode which means that it canbe accessed by one or more applications without a priori knowledge,wherein the access of a file or document is a request that results inthe file or document being opened, viewed, edited, played, listened to,printed, or in a format or outcome desired by a user who has requestedthe access of the file or document.

Secured file, or secured document—defines a type of digital asset thatcannot be accessed without a priori knowledge. Example of a prioriknowledge may include, but not be limited to, a password, a secretphrase, biometric information or one or more keys.

Encrypted file or encrypted document means a file or document that hasbeen encrypted with a cipher (i.e., an implementation of cryptographictechniques).

File key—is one example of a priori knowledge that is also referred toas a cipher key and, once obtained, can be used to unlock or decrypt theencrypted document.

User key—is another cipher key associated with or identifying a user ora group of users and can be used to obtain the file key. According toone format of the secured file, a user key is used to retrieve a filekey that, in turn, unlocks or decrypts the encrypted document while adifferent user key or the same user key may be used to hide or encryptthe file key.

Access privilege—is one or more rights a user may have with respect to asecured file or secured document. A user may only be able to access asecured file from a designated location during a specific period ifhis/her access privilege limits him/her to do so. Optionally, accessprivilege may specify other limitations on a specific host whence useris logged in, a file transfer protocol, an access application (modeland/or version), a permit to grant access privilege to others (e.g. aconsultant) or membership in other groups, etc.

Access rules—are flags or designated permits to limit what a user can dowith a secured file or secured document. According to one embodiment ofthe present invention, at least some of the access rules can be includedin a secured file or secured document. In some cases, the access rulesmay be extensible by a user with appropriate access privilege.

Client device, computer, or machine—interchangeably used herein, is aterminal device typically used by a user to access secured documents.

Server device, computer, or machine—interchangeably used herein, is acomputing device. According to one embodiment, such computing device canprovide access control (AC) management for secured documents that areaccessible from a client machine or a user.

Client module—generally means an executable version of an embodiment ofthe present invention and typically is loaded in a client device todeliver functions, features, benefits and advantages contemplated in thepresent invention.

Server module—generally means an executable version of an embodiment ofthe present invention and typically is loaded in a server device todeliver functions, features, benefits and advantages contemplated in thepresent invention.

Server and Client—unless otherwise specifically or explicitly stated, aserver may mean either a server machine or a server module, a client maymean either a client machine or a client module, and in either case, theparticular meaning shall be evident in the context.

Embodiments of the present invention are discussed herein with referenceto FIG. 1A-7C. However, those skilled in the art will readily appreciatethat the detailed description given herein with respect to these figuresis for explanatory purposes as the invention extends beyond theselimited embodiments.

FIG. 1A shows a basic system configuration in which the presentinvention may be practiced in accordance with one embodiment thereof.Documents or files, such as product descriptions, customer lists andprice schedules, may be created using an authoring tool executed on aclient computer 100, that may be a desktop computing device, a laptopcomputer, or a mobile computing device. Exemplary authoring tools mayinclude Microsoft Office® (e.g., Microsoft Word®, Microsoft PowerPoint®,and Microsoft Excel®), Adobe FrameMaker® and Adobe Photoshop®.

According to one embodiment, the client computer 100 is loaded with aclient module that is a linked and compiled, or interpreted, version ofone embodiment of the present invention and is capable of communicatingwith a server 104 or 106 over a data network (i.e., the Internet or alocal area network). According to another embodiment, the clientcomputer 100 is coupled to the server 104 through a private link. Aswill be further explained below, a document created by an authoring toolis secured by the client module that will be described in detail below.The client module, when executed, is configured to ensure that a secureddocument is secured at all times in a store (e.g., a hard disk or otherdata repository). By virtue of the present invention, the documents arestored in a secured mode and can only be accessed by users with properaccess privileges. In general, an access privilege or access privilegesfor a user may include, but not be limited to, a viewing permit, acopying permit, a printing permit, an editing permit, a transferringpermit, an uploading/downloading permit, and a location permit.

According to one embodiment, a created document is caused to go throughan encryption process that is preferably transparent to a user. In otherwords, the created document is encrypted or decrypted under theauthoring application so that the user is not aware of the process. Akey (referred to herein as a user key) to retrieve a file key to decryptan encrypted document is associated with an access privilege. Only auser with a proper access privilege can access the secured document.

In one setting, a secured document may be uploaded via the network 110to a computing or storage device 102 that may serve as a centralrepository. Although not necessary, the network 110 provides preferablya private link between the computer 100 and the computing device 102.Such link may be provided by an internal network in an enterprise or asecured communication protocol (e.g., VPN and HTTPS) over the Internet.Alternatively, such link may be simply provided by a TCP/IP link. Assuch, secured documents on the computer 100 may be remotely accessed.

In another setting, the computer 100 and the computing or storage device102 are inseparable, in which case the computing or storage device 102may be a local store to retain secured documents or receive securednetwork resources (e.g., dynamic Web contents, results of a databasequery, or a live multimedia feed). Regardless of where the secureddocuments or secured sources are actually located, a user, with a properaccess privilege, can access the secured documents or sources from thecomputer 100 or the device 102 using an application (e.g., InternetExplorer®, Microsoft Word®, or Acrobat Reader®).

The server machine 104, sometimes referred to as a local server, is acomputing device coupled between a network 108 and the network 110.According to one embodiment, the server 104 executes a local version ofa server module of a linked and compiled version of one embodiment ofthe present invention. As will be detailed below, a local version is alocalized server module configured to service a group of designatedusers or client computers, or a location. Another server machine 106,also referred to as a central server, is a computing device coupled tothe network 108. The server 106 executes the server module and providescentralized access control (AC) management for an entire organization orbusiness. Accordingly, respective local modules in local servers, incoordination with the central server, form a distributed mechanism toprovide a distributed AC management. Such distributed access controlmanagement ensures the dependability, reliability, and scalability ofcentralized AC management undertaken by the central server for an entireenterprise or a business location. As will be further explained below,the server module in the central server maintains or interfaces to adatabase that includes, but is not limited to, a list of users andcorresponding access privileges for the entire organization or businessand rules for folders or files, while a local module can be configuredto maintain or interface to a portion or whole of the database, hence,servicing a group of users local to the local server.

FIG. 1B shows a configuration in which a central server and localservers are employed. The configuration may correspond to a largeenterprise having multiple geographic locations or offices. A centralserver 106 maintains a database managing the access privileges and theaccess rules in the entire enterprise. One of the features in thisconfiguration is the underlying capability to provide fault toleranceand efficient AC management for a large group of users. Instead ofhaving the central server 106 performing the AC management for each ofthe users at one single location, a number of local servers 104 (e.g.,104-A, 104-B, . . . and 104-N) are employed in a distributed manner toservice the individual locations or offices. Each of local servers 104executes a local module derived or duplicated from the server modulebeing executed at the central server 106 to manage those users who arelocal to respective local servers 104. The central server 106 cancentralize the AC management in addition to managing the users ifnecessary.

According to one embodiment, a local module can be a customized versionof the server module that runs efficiently for only a few locations or agroup of users. For example, a local server 104-A is only responsiblefor the users or computers 102-A in location A, while a local server104-B is only responsible for the users or computers 102-B in locationB. As a result, even if the central server 106 has to be taken down formaintenance or is not operative at the time a user needs to accesssecured documents, the access control will not be disruptive. Thedetailed operation of the local servers 104 in cooperation with thecentral server 106 will be further described below.

According to another embodiment, a local module is a replicated versionof the server module and exchanges any updates with the server modulewhen connected (e.g. periodically or at request). Depending onimplementation, part or all of the server module can be duplicated in alocal server to ensure that communications with users or their clientmachines are efficient and fault tolerance. As a result, even if thecentral server 106 has to be taken down for maintenance or is notoperative at the time a user needs to access secured documents, theaccess control will not be disruptive. For example, in such a situation,any of the local servers 104 can step up and take the place of thecentral server. When the central server 106 is running or communicatingwith the local servers 104, information collected at the respectivelocal servers about the users or their activities is sent back to thecentral server 106. The detailed operation of the local servers 104 incooperation with the central server 106 in this regard will also befurther provided below.

FIG. 1C shows a configuration suitable for a small group of users. Inthis configuration, no local servers are employed. A server computer 112is loaded with the server module and each of the users or terminalcomputers 116 (only one is shown therein) is loaded with a clientmodule. As a result, the server computer 112 performs the AC managementfor each of the users or the terminal computers 116.

It should be noted that there is no clear distinction between a smallgroup and a large group of users as far as the number is concerned.Given the description herein, those skilled in the art will understandhow to distribute or balance the AC management among one or more othercomputing devices. To facilitate the following description of thepresent invention, the setting shown in FIG. 1B will be assumed. Thoseskilled in the art will understand that the description herein isequally applicable to FIG. 1C or situations in which other possiblesettings between one or more central servers and one or more localservers are desired.

FIG. 1D shows internal construction blocks of a computing device 118 inwhich one embodiment of the present invention may be implemented andexecuted. The device 118 may correspond to a client device (e.g.,computer 100, 102 in FIG. 1A and FIG. 1B or computer 116 in FIG. 1C) ora server device (e.g., server 104, 106 in FIG. 1A and FIG. 1B or server112 in FIG. 1C). As shown in FIG. 1D, the device 118 includes a centralprocessing unit (CPU) 122 interfaced to a data bus 120 and a deviceinterface 124. CPU 122 executes instructions to process data and perhapsmanage all devices and interfaces coupled to data bus 120 forsynchronized operations. The instructions being executed can, forexample, pertain to drivers, operating system, utilities, orapplications. A device interface 124 may be coupled to an externaldevice, such as the computing device 102 of FIG. 1A, hence, the secureddocuments therefrom can be received into memory 132 or storage 136through data bus 120. Also interfaced to data bus 120 is a displayinterface 126, a network interface 128, a printer interface 130, and afloppy disk drive interface 138. Generally, a client module, a localmodule, or a server module of an executable version of one embodiment ofthe present invention can be stored to storage 136 through floppy diskdrive interface 138, network interface 128, device interface 124, orother interfaces coupled to data bus 120. Execution of such module byCPU 122 can cause the computing device 118 to perform as desired in thepresent invention. In one embodiment, the device interface 124 providesan interface for communicating with a capturing device 125 (e.g. afinger print sensor, a smart card reader or a voice recorder) tofacilitate the authentication of a user of the computing device 118.

Main memory 132, such as random access memory (RAM), is also interfacedto data bus 120 to provide CPU 122 with instructions and access tomemory storage 136 for data and other instructions. In particular, whenexecuting stored application program instructions, such as a documentsecuring module in the present invention, CPU 122 is caused tomanipulate the data to achieve results contemplated by the presentinvention. Read-Only Memory (ROM) 134 is provided for storing executableinstructions, such as a basic input/output operation system (BIOS) foroperation of keyboard 140, display 126, and pointing device 142, ifthere are any.

Referring now to FIG. 2A, an illustration diagram of securing a createddocument 200 is shown. After the document 200 is created with anapplication or authoring tool (e.g., Microsoft Word®), upon anactivation of a “Save,” “Save As” or “Close” command or automatic savinginvoked by an operating system, the application, itself, or anapplication that is previously registered with the server, the createddocument 200 is caused to undergo a securing process 201. The securingprocess 201 starts with an encryption process 202, namely the document200 that has been created or is being written into a store is encryptedby a cipher with a file key. In other words, the encrypted documentcould can not be opened without the file key (i.e., a cipher key).

A set of access rules 204 for the document 200 is received andassociated with a header 206. In general, the access rules 204 determineor regulate who and/or how the document 200, once secured, can beaccessed. In some cases, the access rules 204 also determine or regulatewhen or where the document 200 can be accessed. Typically, a header is afile structure, small in size and includes, or perhaps links to,security information about a resultant secured document. Depending on anexact implementation, the security information can be entirely includedin a header or pointed to by a pointer that is included in the header.According to one embodiment, the access rules 204, as part of thesecurity information, is included in the header 206. The securityinformation further includes the file key and, in some cases, anoff-line access permit (e.g. in the access rules) should such access berequested by an authorized user. The security information is thenencrypted by a cipher with a user key associated with an authorized userto produce encrypted security information 210. The encrypted header, ifno other information is added thereto, is attached to the encrypteddocument 212 to generate a secured document 208.

It is understood that a cipher may be implemented based on one of manyencryption/decryption schemes. Examples of such schemes may include, butnot be limited to, Data Encryption Standard algorithm (DES), Blowfishblock cipher and Twofish cipher. Therefore, the operations of thepresent invention are not limited to a choice of those commonly-usedencryption/decryption schemes. Any encryption/decryption scheme that iseffective and reliable may be used. Hence, the details ofencryption/decryption schemes are not further discussed herein so as toavoid obscuring aspects of the present invention.

In essence, the secured document 208 includes two parts, the documentitself, and the corresponding security information therefor, both are inencrypted form. To access the document, one needs to obtain the file keythat is used to encrypt the document and is now included in theencrypted security information. To obtain the file key, one needs to beauthenticated to get a user or group key and pass an access test inwhich the access rules in the security information are measured againstthe user's access privilege.

According to one embodiment, the encrypted security information thatincludes the access rules or the header is placed at the beginning ofthe encrypted document (data portion) to facilitate early detection ofthe secured nature of a secured document. One of the advantages of suchplacement is to enable an access application (i.e., an authoring orviewing tool) to immediately activate a document securing module todecrypt the header. Upon the success of the decryption of the headerwith an authenticated user key, the access rules can be checked againstthe user's access privilege. If the user who requested the secureddocument does have the proper access privilege, the clear contents ofthe document will be loaded into the access application, otherwise adenial notification (e.g., a message or a blank document) is sent to theuser. However, the encrypted security information or the header may beplaced anywhere around or in the encrypted document and sometimes maynot be embedded contiguously in the encrypted data portion. By thevirtue of the present invention, the encrypted header is always attachedto the encrypted data portion, namely, the security information stayswith the document being secured. This integrated mechanism facilitiesthe transporting of secured documents to other locations without theloss of the security information therein.

One of the features in the present invention is that the document beingsecured is transparent to the user. In other words, a secured documentor file is configured to have a file extension identical to that of thefile before being secured so that an application designated to accessthe file can be executed to access the secured file. For example, anewly created Microsoft word document, xyz.doc, can be accessed by anapplication WINWORD.EXE. After it goes through the securing process, thesecured document is maintained to keep the same file name, i.e.,xyz.doc, which still can be accessed by the same applicationWINWORD.EXE, except now the application may fail to open the document ifthe access rules therein do not permit a user to do so.

Alternatively, a secured document in a folder appears substantiallysimilar to a regular document and launches the same application whenactivated except the application will fail to access the contentstherein. For example, icons or file names of secured documents mayappear in a different color or with a visual indicator to distinguishfrom non-secured documents. When a secured document is unintentionallyends up in a machine or readable medium (e.g., CD or disk), if a user ofthe machine or a machine attempting to read the readable medium has noproper user key or if the user cannot be authenticated, the secureddocument will not be successfully accessed.

It should be noted that the header in a secured document may beconfigured differently than noted above of a few formats herein withoutdeparting the principles of the present invention. For example, asecured document may include a header with a plurality of encryptedheaders, each can be accessible only by one designated user or a groupusers. Alternatively, a header in a secured document may include morethan one set of security information, each set being for one designateduser or a group of users while a single file key can be used by all.Some or all of the access rules may be viewed or updated respectively byusers who can access the secured document.

As will be further described below, to access a secured document, a userneeds a user key or keys to decrypt the encrypted security informationor header first. In one embodiment, the key or keys are associated witha user's login to a local server or a central server. Appropriate accessprivilege associated with the user is validated if the user has beenauthenticated or previously registered with the server and properlylogged in. Depending on the permission or the access privileges, theaccess rules in the secured document determine whether the contents inthe document shall be revealed to the user.

According to one embodiment, the access rules are present in a markuplanguage, such as HTML and SGML. In a preferred embodiment, the markuplanguage is Extensible Access Control Markup Language (XACML) that isessentially an XML specification for expressing policies for informationaccess. In general, XACML can address fine grained control of authorizedactivities, the effect of characteristics of the access requestor, theprotocol over which the request is made, authorization based on classesof activities, and content introspection (i.e., authorization based onboth the requestor and attribute values within the target where thevalues of the attributes may not be known to the policy writer). Inaddition, XACML can suggest a policy authorization model to guideimplementers of the authorization mechanism.

The following shows an example of the access rules expressed in XACML:

  <rule>  <doc_type>   PDF  </doc_type>  <grantor name=″ACCTG″/> <grantee name=″MKTG″/>  <grantee name=″PR″/>  <action>   VIEW </action>  <action>   PRINT  </action>  <conditions> <delivery_channels>   HTTPS  </delivery_channels>  <min_time_day>  1700  </min_time _day>  <expiry_date>   3 Aug, 2002  </expiry_date> </conditions> </rule>

The literal meaning of the above example is that “any new PDF documentscreated by ACCTG (accounting group), can be VIEWed and PRINTed by MKTG(marketing group) and PR (public relationship group), on the conditionthat the documents are downloaded over secured HTTP, accessed before5:00 PM in the day, before Aug. 3, 2002.”

FIG. 2B illustrates an exemplary structure of a secured document 220including a header 222 and an encrypted portion 224. The header 222includes a security information block 226 having encrypted securityinformation that essentially controls the access to the encrypteddocument 224. In a certain implementation, the header 222 includes aflag 227 (e.g., a predetermined set of data) to indicate that thedocument 220 is secured. The security information block 226 includes oneor more user IDs 228, access rules 229, at least one file key 230 andother information 231. The user IDs 228 maintain a list of authorizedusers who may be measured against by the access rules 229 before thefile key 230 can be retrieved. The access rules 229 determine at leastwho and how the encrypted document 224 can be accessed. Depending on animplementation, the other information 231 may be used to include otherinformation facilitating a secure access to the encrypted document 224,the example may include version numbers or author identifier.

In general, a document is encrypted with a cipher (e.g., a symmetric orasymmetric encryption scheme). Encryption is the transformation of datainto a form that is impossible to read without appropriate knowledge(e.g., a key). Its purpose is to ensure privacy by keeping informationhidden from anyone to whom it is not intended, even those who haveaccess to other encrypted data. Decryption is the reverse of encryption.Encryption and decryption generally require the use of some secretinformation, referred to as a key. For some encryption mechanisms, thesame key is used for both encryption and decryption; for othermechanisms, the keys used for encryption and decryption are different.For the purpose of controlling the access to the document, the key orkeys, referred collectively to as a file key, may be the same ordifferent keys for encryption and decryption and are preferably includedin the security information contained in or pointed to by the headerand, once obtained, can be used to decrypt the encrypted document.

To ensure that the key is not to be retrieved or accessible by anyone,the key itself is guarded by the access privileges and rules. If a userrequesting the document has the proper access privileges that can begranted by the access rules, the key will be retrieved to proceed withthe decryption of the encrypted document.

To ensure that the security information or the header (if no flag isimplemented) is not readily revealed, the header itself is encryptedwith a cipher. Depending on an exact implementation, the cipher for theheader may or may not be identical to the one used for the document. Thekey (referred to as a user key) to decrypt the encrypted header can, forexample, be stored in a local store of a terminal device and activatedonly when the user associated with it is authenticated. As a result,only an authorized user can access the secured document.

Optionally, the two encrypted portions (i.e., the encrypted header andthe encrypted document) can be encrypted again and only decrypted by auser key. In another option, the encrypted portions (either one or all)can be error checked by error checking portion 225, such as usingcyclical redundancy check, to ensure that no errors have incurred to theencrypted portion(s) or the secured document 220.

FIG. 2C.1 illustrates an exemplary structure of a secured document 236including a header 238 and an encrypted portion 239. The header 238permits four different entities 240-243 to access the secured document236. The four different entities 240-243 include two individual usersand two group users, wherein the group users mean that everyone in thegroup can access the document with the same privileges. The twoindividual users have two different access privileges. User A can onlyread the document while user D can edit and read the document. Whileeveryone in Group B can read and edit the document, everyone in Group Ccan only print the document. Each entity has a corresponding IDassociated with the corresponding users and its own access rules.According to one embodiment, the header 238 in the secured document 236is partitioned into corresponding four sub-headers 240-243, eachdesignated to one user or group and keeping a file key therein andencrypted with a separate user key. In other words, when User A isrequesting the secured document 236, only the header 240 designated toUser A is decrypted with a user key (e.g., key A) belonging to the userA and authenticated with the user, the rest of the sub-headers 241-243remain encrypted. In any case, once one of the sub-headers 241-243 isdecrypted, the secured document can be decrypted with a key (e.g., filekey) retrieved from the decrypted sub-header.

FIG. 20.2 illustrates another exemplary structure of a secured document250 including a header 252 and an encrypted portion 254. The header 252further includes a user block 256 and a rules block 258. The user block256 includes a clear portion and an encrypted portion 260. The clearportion includes user/group ID(s) and block version number(s). Theencrypted portion 260 is encrypted with a user key according to acipher. If there are N number of distinctive groups/users with possibledifferent access privileges, there will be N such encrypted portions,each encrypted with a corresponding user key. The encrypted portion 260includes, among other things, the file key that, once retrieved, can beused to decrypt the encrypted data portion 254. In addition, theencrypted portion 260 includes the cipher information to facilitate theencryption/decryption of the encrypted portion 254.

The rules block 258 can be encrypted individually or with the encrypteddocument 254 using the file key that is eventually stored in the userblock 256. One of the advantages of using the file key instead of theindividual user key to encrypt the rules block 258 is to provide amechanism for all authorized users/groups to view who has what accessrules and rights. According to one embodiment, a random number or aresult from an initialization process (e.g. a vector) may be added inthe beginning of the rules block 258 to prevent an attack against therules block 258.

FIG. 20.3 shows an exemplary header 266 corresponding to that of thesecured document structure in FIG. 2C.2. The header 266 includes anumber of segments. In addition to those segments in clear mode,segments 267-269 are encrypted. Specifically, the secured file isconfigured to be accessed by two groups: marketing and engineering. Allusers in the two groups are supposed to be able to access the file withan authenticated user key. According to one embodiment, the segment 267is encrypted with a user key specifically designated to marketing users,while the segment 268 is encrypted with a user key specificallydesignated to engineering. However, both of the segments 267 and 268could be respectively encrypted with a single user key. In any event,the encrypted segments in the header 266 include a file key 270 inaddition to corresponding cipher information about the cipher beingused.

The rules block (i.e., a segment) 269 includes two sets 271 and 272 ofaccess rules (details on rules not shown), one for each of the two usergroups. The rules block 269 is encrypted with a key, such as the filekey 270 or some other key depending on what cipher is used. According toone embodiment, one of the encrypted segments in the user blocks 267 and268 shall be decrypted 269 with an authenticated user key to retrievethe file key 270. Before the file key 270 is applied to the decryptionof the encrypted data portion, the rules block 269 is decrypted with thefile key 270. The access rules are then measured against the accessprivilege of the user. If the user is not permitted to access thesecured document, the file key 270 will not be applied to the decryptionof the encrypted data portion. If the user is permitted to access thesecured document, the file key 270 will then be applied to thedecryption of the encrypted data portion.

It should be noted that FIG. 2C.1, FIG. 2C.2 and FIG. 2C.3 are onlyexemplary structures of secured documents. In an alternativeimplementation, the file key necessary to decrypt the document may beencrypted alone and kept in a separate block in the header. The file keybecomes retrievable when one of the sub-headers (no longer keeping thefile key) is decrypted. In still another alternative implementation, oneor more flags or messages may be included in the security information ofa secured document, the flags or messages indicate how secure thesecured document can be. For example, a secured document can beclassified as a normal, confidential, secret or a top-secret document,requiring different level of access. Accordingly, multiple-levels ofencryption on the file key and/or access rules may be employed to ensurethat only an authorized user or users are permitted to access thesecured document. Other implementation options are also possible giventhe description herein and are not to be listed one by one to avoidobscuring aspects of the present invention.

FIG. 2D shows an exemplary graphic user interface (GUI) 275 that can beused to establish or create access rules. The GUI 275 can be activatedand/or displayed when a user finishes with a secured document and isready to save it into a designated place (e.g., a folder or arepository) or a clear or new document is ready to be placed into adesignated place. According to one embodiment, all data in thedesignated place will have substantially similar access rules. Dependingon an exact implementation, the GUI 275 can be dynamically generated orcontrolled by the central server to include users who may have the needto access the data in that designated place. The GUI 275 facilitates thedetermination of the access rules that the user intends to impose. Asshown in FIG. 2D, a selected group of users can be selected to add intoan access list 276. Actions 277 determine how the data in the designatedplace can be accessed. The actions 277 can be set using the GUI 275. Asa result, the parameters defining the access rules can be graphicallydetermined and now gathered from the GUI 277 to be included in thedocument (e.g., in the security information of the header). In oneembodiment, the access rules are kept in a temporary file (e.g., in amarkup language format) associated with a designated folder andoptionally encrypted. The temporary file can then be attached to anencrypted portion when the document is being written as a secured fileinto a local store.

Sometimes, a user may have a need to export or import a set ofpredefined access rules. In this case, the temporary file having theaccess rules may be exported, downloaded, or imported into anotherdevice or folder. The exportation/importation of access rules providesconvenience for a user because the user need not create the access rulesfrom scratch.

One of the features for setting up a set of access rules for aparticular place or folder is to provide a securing mechanism for usersto create secured documents without specifying as to who/how/when/wherethe documents can be accessed. FIG. 2E shows a directory structure 280including a clear folder 281 and a secured folder 282. The clear folder281 is generally for storing system files or files that are not intendedto be protected. The secured folder 282 includes multiple subfoldersthat can be structured respectively for each access level. For example,a document “employee list” can be accessed by anyone who has accessprivileges to access level A. Similarly, documents “product milestone”and “product specification” or “product schedule” can be accessed byanyone who has an access privileges to folder 284 for access level B andto folder 286 for access level C, respectively. Likewise, a createddocument, if placed in folder “design team 2”, will be automaticallyencrypted with the corresponding access rules that will permit onlythose who has access privileges to access level B. In this embodimentthe access levels are hierarchical, meaning that a user with accesslevel A authorization can access not only access A items but also thelower access levels B and C which are subsets of access level A.

Unlike prior art systems in which documents to be secured are encryptedby an encryption process initiated by a user, one of the features in thepresent invention is to activate a cipher process (i.e.,encryption/decryption process) transparently as far as the user isconcerned. In other words, the user is not made aware that a document isbeing made secured through the cipher process while being written into astore.

FIG. 3 shows an exemplary implementation 300 of how a document securingmodule (DSM) 302 interacting with and operating within an operatingsystem 304 (e.g., WINDOWS 2000) to ensure that a document is made securein a manner that is transparent to the user.

An application 306 (e.g. a server registered application, such asMicrosoft Word) operates over operating system (OS) 304 and may beactivated to access a document stored in a store 308. The store 308 maybe a local storage place (e.g., hard disk) or remotely located (e.g.,another device). Depending on the security nature (secured vs.non-secured) of the document being accessed, the DSM 302 may activate acipher module 310. According to one embodiment, the DSM 302 is analogousin many ways to a device driver that essentially converts more generalinput/output instructions of an operating system to messages that adevice/module being supported can understand. Depending on the OS inwhich the present invention is implemented, DSM may be implemented as aVxD (virtual device driver), a kernel, or other applicable format. Thecipher module 310 is included in or controlled by the DSM 302 and can beactivated for operations when a secured document is involved.

In operation, a user selects a secured document that is associated withan application 306 (e.g., MS Word®, PowerPoint®, or printing). Theapplication 306 acting on the secure document calls an API (e.g.,createFile, a Common Dialog File Open Dialog with Win 32 API in MSWindows®) to access the installable file system (IFS) manager 312. If itis detected that an “Open” request is made from the application 306, therequest is passed to an appropriate file system driver (FSD) 314 toaccess the requested secured document. At the same time, the ciphermodule 310 is activated and an authenticated user key is retrieved froma local store to decrypt the header in the requested secure document. Ifthe encrypted header is decrypted and the access rules therein aremeasured successfully against the user's access privileges, then a filekey is retrieved from the header of the secured document and the ciphermodule 310 proceeds to decrypt the encrypted document in the DSM 302.The clear contents are then returned to the application 306 through theIFS manager 312. For example, if the application 306 is an authoringtool, the clear contents are displayed. If the application 306 is aprinting tool, the clear contents are sent to a designated printer.

If it is detected that a “New” request is made, which means a secureddocument is being created or authored, a file key is generated in theDSM 302 (e.g., by the cipher module 310) and the file key will besubsequently used to encrypt the contents in a document being created.To ensure that the local store always has the encrypted documents, everytime, a “Write” request (e.g., a “save” command in Microsoft Word) ismade manually by a user or automatically by the application 306 or theOS 304, whatever contents in the document being processed or authoredare encrypted by the cipher module 310 with the file key in the DSM 302.When a “Close” request is made, the file key is stored in a header thatalso includes whatever access rules that the user has applied thereto.The header is then encrypted with an authenticated user key and attachedto the encrypted document before the document is sent to the appropriateFSD (e.g., 314) for storage in the store 308 (e.g., a folder or adesignated location). As a result, a secured document is created.

In another embodiment, an operating system (OS) access, known as theProcessID property, can be used to activate an application (as anargument to the AppActivate method). The parameter ProcessID identifiesthe application and an event handler thereof takes necessary parametersto continue the OS access to the Installable File System (IFS) Manager312 that is responsible for arbitrating access to different file systemcomponents. In particular, the IFS Manager 312 is configured to act asan entry point for processes such as opening, closing, reading, writingfiles and etc. With one or more flags or parameters passed along, theaccess activates the DSM 302. If the document being accessed by theapplication is regular (non-secured), the document will be fetched fromone of the File System Driver (FSD) (e.g., FSD 314) and passed throughthe DSM 302 and subsequently loaded into the application through the IFSManager 312. On the other hand, if the document being accessed by theapplication is secured, the DSM 302 activates the cipher module 310 andproceeds to obtain an authenticated user key to retrieve the accessrules therein. If the access privileges satisfy the access rules, a filekey will be retrieved to decrypt the encrypted data portion of thesecured document by the cipher. As a result, the data portion or thedocument in clear mode will be loaded into the application through theIFS Manager 312.

According to one embodiment, the DSM 302 resides on a local disk (e.g.,storage 136 of FIG. 1D) in a file that is structured like a dynamic-linklibrary (DLL), typically with a SYS or IFS extension, and is loadedduring system initialization. Once the DSM 302 is installed andinitialized, a kernel communicates with it in terms of logical requestsfor file opens, reads, writes, seeks, closes, and so on. Through the IFSManager 312, the FSD 314 translates these requests—using controlstructures and tables found on the volume itself—into requests forsector reads and writes for which it can call special kernel entrypoints called File System Helpers (FsHlps). The kernel passes thedemands for sector I/O to an appropriate device driver and returns theresults (e.g., the requested document) to the FSD 314. Upon receivingthe results from the FSD 314 indicating that the requested document issecured, the DSM 302 activates the cipher module 310 included therein todecrypt the document if permitted by the access rules in the secureddocument.

FIG. 4A shows a flowchart of a process 400 of securing a document beingcreated according to one embodiment of the present invention. At 402, ablank document is opened or created by an authoring application chosenand activated by a user. In a preferred procedure, the user may save thedocument in a folder that has already setup with a set of access rules.At 404, the set of predetermined access rules is received, preferably,in a markup language. As described above, the access rules may also bereceived by importation of a previously created file including desirableaccess rules, defaults of the user access privileges or individuallycreated user access privileges.

At 406, a secret cipher key (i.e., a file key) is generated from acipher module for the document and typically stored in a temp file thatis generally not accessible by an ordinary user. The temp file will beerased automatically when the secured document is done (e.g., at a“Close” command from the application). At 408, the document is checkedto see if a request to write the document into a local store is made. Ifsuch request is detected (which could be made manually by the user orperiodically by the authoring tool or an OS), the document is encryptedwith the file key at 410. One of the features in the present inventionis that the stored document is always encrypted in storage even if it isstill being processed (e.g., authored, edited, or revised). When theuser is done with the document, a “Close” request is activated to closethe document. At 412, such a request is detected. As soon as suchrequest is received, it means that a secured version of the document isbeing written into the store. At 413, the access rules and the file keyare included in security information that is encrypted with theauthenticated user key. Depending on implementation, a flag or signatureand the security information can be included in the header.Alternatively, the header could include the security information withouta flag. At 414, the header is attached to the encrypted document from410 and subsequently the secured document is placed into the store at418.

As described above, the secured document includes two encryptedportions, the header with encrypted security information and theencrypted data portion (i.e., the encrypted document). The two parts inthe secured documents are encrypted respectively with two differentkeys, the file key and the user key. Alternatively, the two encryptedportions may be encrypted again with another key (or use the same userkey) at 416.

In the case that there are a number of sets of access rules, each for aparticular user or a group of users, it can be understood that theencrypted access rules at 413 are integrated with other sets of theencrypted access rules in a rules block as illustrated in FIG. 2C.2. Assuch, an access from one user or group will not affect other users orgroups but the other users or groups will see perhaps an updated versionof the encrypted document.

FIG. 4B shows a flowchart of an exemplary process 430 of receiving theaccess rules. The process 430 may be performed at 404 in FIG. 4A tofacilitate the process of securing a document. To put less burden on auser, the present invention, as will be further described below,provides a one-time authentication mechanism, which significantlydiffers from prior art systems in which user authentication is requiredfor each access to a secured document. In operation, once a user hasbeen authenticated to access a secured document, authentication of theuser would not be required. Also, once the user is authenticated, he/shecan access other secured documents without being authenticated again aswell.

Generally, there are at least two situations in which the user has to beauthenticated before being able to access secured documents. In a firstsituation, a client machine is coupled to a network (e.g., LAN), a userthereof needs to authenticate himself/herself by providing his/hercredential information when it is a first time to use the clientmachine. Commonly, the credential information is a set of username andpassword. If the user is registered, the provided credential informationwill match the user's identity in the server and hence the user will beauthenticated. Once the user is authenticated, a user key associatedwith the user can be activated or authenticated. The user can now usethe client machine and subsequently access secured documents. Otherpossible credential information may include the user's biometricinformation such as finger print and voice, etc. that can be obtainedfrom a dedicated device attached to the client machine. One such devicemay be a finger print sensor from DigitalPersona, Inc. at 805 VeteransBoulevard, Suite 301, Redwood City, Calif. 94063. When biometricinformation of the user is captured, it can verify what the user claimsto be. Depending on an implementation, a user key may be locally storedor retrieved remotely. In any event, the user key, before authenticated,is preferably in an illegible format (e.g., encrypted or scrambled witha pass phrase associated with the user) to prevent a possible hackingthereto. The user's authentication or the biometric information of theuser may be used to validate, retrieve or authenticate the user key. Asa result, an authenticated user key in clear form is readily availablefor the user to access any secured document. In a second situation, aclient machine coupled to a network can accommodate whatever the userthereof intends to do except for requesting a secured document. When itcomes to a request to a secured document, the user authenticationprocess is invoked.

Referring back to FIG. 4B, the user authentication process is invoked,communication to a server (e.g., server 104 or 106) is checked at 432.

If it is detected that no communication to the server is available,which may mean that the client machine may not be on a network or theserver is down or other causes, the user may have at least threeoptions. First, the user can now access only non-secured documents ormay generate secured documents at 434 if a public user key is availableor retained in the client machine. Second, the user can keep trying tocommunicate with the server, in which case the process 430 goes back to432 till a secured communication link is established. Third, the usermay take advantage of another feature offered by the present invention,offline access at 433. In short, the user may access a limited number ofsecured documents on the client machine, the details of which will beprovided below.

It is assumed that a secured link (possibly over HTTPS, VPN, SSL) isestablished between the client machine and the server. Now the process430 goes to 436 where the user and/or the client machine itself needs tobe authenticated. In some cases, it is needed to ensure that a secureddocument can only be accessed by a user from a permitted machine. Hence,in such cases, it is necessary to authenticate the user as well as theclient machine from which the user is to access secured documents.

As far as the user is concerned, the user needs to furnish his/hercredential information (e.g., username/password) to be verified. Oncethe user is authenticated by the server, the client machine needs to beauthenticated. To ensure that a user is confined to one or moredesignated local computers and can only access secured document fromthese designated local computers, there is a determination of whetherthe user is using one of the designated local computers to access thesecured documents. In operation and at 436, the client machine'sidentifier (e.g., a number from a network card) is checked by the serverto determine: 1) whether this client machine can be used to accesssecured documents; and 2) whether the combination of the client machineand the user is valid. If the check process is successful, the process430 goes to 438 otherwise the user can only work on non-secureddocuments at 434.

A user key associated with the user is authenticated at 438. At thispoint, the user is able to access secured documents. Certainly, thecorresponding access privileges with the user as well as the accessrules in a secured document ultimately determine whether the user canopen the secured document.

After the user and the client machine the user is using are respectivelyauthenticated or verified, the user key is activated (e.g., ready touse). The user key may have been newly generated or stored in anillegible format. The user authentication process retrieves the user keyto a form that can be readily used and/or get the user key to the clientmachine.

It is assumed that the user is accessing or creating a secured document.At 440, the user access privilege originally set up by an administratoris activated, which determines when, where and what kind of secureddocuments he/she can access. Likewise, the default access rules forspecific folders to store secured documents may be available for viewingor gathered at 442 and could be saved into a temp file to be eventuallyattached (in an encryption format) to an encrypted document beingaccessed or created by the user.

Although the description of the process 430 in FIG. 4B is based on theuser authorization process formed in conjunction with a server. It isclear to those skilled in the art that the description is readilyapplied to other means for conducting the user authentication. Forexample, the user key can be authenticated, validated, or retrieved bybiometric information of the user as described above.

Referring now to FIG. 4C, there is shown a flowchart of process 450 ofaccessing a secured document according to one embodiment and shall beunderstood in conjunction with FIG. 3. At 452, an application islaunched with a document being specified, for example, WINWORD.EXE isactivated to open a file named xyz.doc. As explained above, a handlerfrom the OS identifies the application and enters the OS wherein the IFSmanger is called upon at 454. The IFS manger activates a DSM module at456 and at the same time, the IFS manger passes the handler to receiveat 458 the selected document from a store. As the selected documentpasses through the DSM module, the selected document is determinedwhether it is secured or non-secured at 460. In general, there are atleast two ways to examine the secure nature of the selected document. Afirst possible way is that the DSM module looks for a flag at thebeginning of the document. As described above, in some secureddocuments, a flag, such as a set of predetermined data, is placed in theheader to indicate that the document being accessed is secured. If nosuch flag is found, the process 450 goes to 470, namely, the selecteddocumented is assumed non-secured and thus allowed to pass the DSMmodule and loaded into the application from the IFS manger. A secondpossible way is that the DSM module looks for a header in a secureddocument. Being a secured document, there is a header attached to anencrypted data portion. The data format of the header shall be irregularin comparison with the selected document if it were non-secured. If theDSM module determines that the selected document has no irregular dataformat as required by the application, the process 450 goes to 470,namely, the selected documented is assumed to be non-secured and thusallowed to pass through the DSM module and be loaded into theapplication from the IFS manger.

Now if it is determined at 460 that the selected document is indeedsecured, the process 450 goes to 462 wherein the header or securityinformation therein is decrypted with the authenticated user key. At464, the access rules in the decrypted security information areretrieved. At 466, the access rules are compared to (or measuredagainst) the access privileges associated with the user. If themeasurement fails, which means that the user is not permitted to accessthis particular document, a notification or alert message may begenerated by the DSM module to be displayed to the user at 467.Alternatively, the application itself can display an alerting messagewhen it fails to open the selected document. If the measurement passessuccessfully, which means that the user is permitted to access thisparticular document, a file key is retrieved from the securityinformation at 468 and used to decrypt the encrypted data portion in theselected (secured) document by a cipher module activated by the DSMmodule. As a result, at 470 the decrypted document or clear contents ofthe selected document is loaded into the application from the IFSmanger.

Referring now to FIG. 5A, there is shown a functional block diagram of aserver device 500 in which a server module 502 resides in a memory space503 and is executable by one or more processors 501. The server device500 also includes a network interface 504 to facilitate thecommunication between the server 500 and other devices on a network anda local storage space 505. The server module 502 is an executableversion of one embodiment of the present invention and delivers, whenexecuted, features/results contemplated in the present invention.According to one embodiment, the server module 502 comprises anadministration interface 506, an account manager 508, a user key manager510, a user monitor 512, a local server manager 514, a partner accessmanager 516, an access report manager 518, and a rules manager 520.

Administration Interface 506:

As the names suggests, the administration interface 506 facilitates asystem administrator to register users and grant respective accessprivileges to the users and is an entry point to the server module fromwhich all sub-modules or the results thereof can be initiated, updatedand managed. In one embodiment, the system administrator sets uphierarchy access levels for various active folders, storage locations,users or group of users. For example, as shown in FIG. 5B.1, differentusers can be assigned to different access privileges. User A may be anexecutive or a branch supervisor who has all the access privileges toany secured documents. User B has limited access privileges whileeveryone in user group C shares the same access privileges. Theprivileges may include, but not be limited to: open, edit write, print,copy, download and others. Examples of the other privileges are:altering access privileges for other users, accessing secured documentsfrom one or more locations, and setting up a set of access rules for afolder different from those previously set up (perhaps by the systemadministrator). The respective user IDs assigned to the users facilitatethe management of all the users. Unless specifically stated differently,a user or a corresponding user ID is interchangeably used herein toidentify a human user, a software agent, or a group of users and/orsoftware agents. Besides a human user who needs to access a secureddocument, a software application or agent sometimes needs to access thesecured document in order to proceed forward. Accordingly, unlessspecifically stated, the “user” as used herein does not necessarilypertain to a human being. In general, a user who will access a secureddocument is associated with a user key to allow an encrypted header in asecured document to be unlocked (decrypted). The expiration orregeneration of a user key may be initiated by the system administrator.According to one embodiment, the administration interface 506 is a usergraphic interface showing options for various tasks that anauthenticated system administrator or operator may need to perform.

Account Manager 508:

Essentially, the account manager is a database or an interface to adatabase 507 (e.g., an Oracle database) maintaining all the registeredusers and their respective access privileges, and perhaps correspondinguser keys (e.g., private and public keys). In operation, the accountmanager 508 authenticates a user when the user logs onto the server 500and also determines if the user can access secured documents from thelocation the user is currently at. In general, the account manager 508is where an enterprise may be able to control its users.

User Key Manager 510:

This module is configured to keep a copy of keys for each of the usersin an organization. According to one embodiment, the user key manager510 is not activated to retrieve the keys therein. In some situations, akey can be retrieved by the system administer to access a secureddocument in case the key in a client machine is corrupted or the user orusers who have the access privilege to access the secured document areno longer available. Optionally, the user key manager 510 is configuredto expire some or all of the keys therein for security reasons. In onecase, a user is no longer with the organization, the corresponding userkey can be manually expired in the user key manager 510. In anothercase, a user's key has been used for a long period, the user key manageris configured to expire the old user's key and replace it with a newlygenerated key. Such replacement can be made transparent to the user andthe new key may be uploaded to a client machine next time the user logson therefrom. According to another embodiment, the user key manager 510keeps a private key and a public key for each of the users. The publickey is used to encrypt security information in a header and the privatekey is used to decrypt the security information in the header. FIG. 5B.2shows an exemplary table that may be maintained by the user key manager510 in conjunction with account manager 508.

User Monitor 512:

This module is configured to monitor user's requests and whereabouts.Typically, a user is granted to access secured documents from one ormore designated locations or networked computers. If a user has a higheraccess privilege (e.g., to permit to access from other than thelocations or networked computers), the user monitor 512 may beconfigured to ensure that the user can have only one access from one ofthe registered locations or computers at all times. In addition, theuser monitor 512 may be configured and scheduled to periodically push orrespond to a pull request of an update of access privileges.

Local Server Manager 514:

This module is designed to be responsible for distributing anappropriate local module for a local server servicing a predeterminedlocation or a predetermined group of users. According to one embodiment,the local server manager 514 replicates some or all of the server module502 being executed on the server 500 and distributes the replicated copyto all the local servers. As a result, a user can access secureddocuments anywhere within the network premises covered by the localservers without being authenticated at a single central server, namelythe server 500. According to another embodiment, the local servermanager 514 replicates some of the server module 502 being executed onthe server 500 and distributes the replicated copy to a correspondinglocal server. In this embodiment, each of the local servers will haveits own customized replication from the server module 502. When a userhas a sufficiently high access privilege (e.g., to permit to access frommore than one locations or one computers) and the user monitor 512 candetect that the user has moved from an originally configured locationserviced by one local server to another permitted location serviced byanother local server. Upon a notification, the local server manager 514is configured to reconfigure a local module for the local server thatthe user has newly contacted. Namely, the user is added as a user to thelocal server being newly contacted. If it is required that the user canaccess from only one computer at a time, regardless where it is in anorganization, the local server manager 514 can also reconfigure thelocal module for the local server that the user has previouslycontacted. As a result, the user is removed from the local server thatthe user previously contacted.

Partners Access Manager 516:

A special module to manage non-employees accounts. The non-employees maybe consultants to a business that requires the consultants to accesscertain secured documents. The partners access manager 516 generallyworks in accordance with other modules in the server but puts additionalrestrictions on such users being directly managed by the partners accessmanager 516. In one application, the partners access manager 516generates a request to the user key manager 510 to expire a key or keypair for a consultant when an engagement with the consultant ends.

Access Report Manager 518:

A module is configured to record or track possible access activities andprimarily works with a corresponding sub-module in a client module beingexecuted in a client machine. The access report manager 518 ispreferably activated by the system administrator and the contentsgathered in the access report manager 518 shall be only accessed by thesystem administrator or with authority.

Rules Manager 520:

In general, the rules manager 520 is an enforcement mechanism of variousaccess rules. According to one aspect, the rules manager 520 isconfigured to specify rules based on i) data types (e.g., MicrosoftWord), ii) group users or individual, iii) applicable rights, and iv)duration of access rules.

Typically, a set of rules is a policy. A policy can be enabled,disabled, edited, deployed and undone (e.g., one or two levels).Policies managed by the rules manager 520 operate preferably on a globallevel. They are downloaded to the client machine during the loginprocess (after the user is authenticated) and can be updateddynamically. In addition, respective policies may be associated withactive folders (i.e., those designated places to store secureddocuments). These polices are also downloaded and updated on the clientmachine. Simple policies are also embedded in the document and providedocument specific policies. According to one embodiment, a header isreceived by a local server from a client and the access rules from theheader are retrieved. The key manager 510 is called upon to decrypt theencrypted security information in the header. The rules manager 520 isalso called upon to parse the access rules from the security informationand evaluate or measure the access rules against the access privilege ofthe user to determine whether the secured document can be accessed bythe user. If the evaluation or measurement succeeds, a file key isretrieved and sent back to the client.

It should be pointed out that the server module 502 in FIG. 5A listssome exemplary modules according to one embodiment of the presentinvention and not every module in the server module 502 has to beimplemented in order to practice the present invention. Those skilled inthe art can understand that given the description herein, variouscombinations of the modules as well as modifications thereof withoutdeparting the spirits of the present invention, may achieve variousdesired functions, benefits and advantages contemplated in the presentinvention.

Referring now to FIG. 5B.3, there is shown a flowchart of a process 510to update a user key 510. As described above, in some cases, there is aneed to expire a user key and update the expired user key with a newone. Preferably, the process 510 is proceeded unnoticeably to the user,such as when the user logs onto the server. Optionally, the user isnotified of the updating of his/her user key. In general, there can beat least two situations that demand the expiration/updating of a userkey. When a user terminates with an organization, for security reasons,it is desirable to invalidate the user key associated with the user.Accordingly, at 511, the process 510 awaits a manual request. When asystem administrator is notified of a departing employee, such a manualrequest can take place.

Alternatively, an organization or the system administrator can set up atime table to expire every user key under the management, say every sixmonths, to replace the expired user key with a new one. At 512, theprocess awaits a timed request.

In any case, when the process 510 is caused to proceed forward with arequest from 511 or 512, at 514, the key manager in the server module isconsulted with to look up a user key being targeted or sought. Once thetarget key is retrieved, a corresponding new key is generated at 516with a cipher. According to one embodiment, the cipher in use is thesame one or substantially identical one used in a client module toencrypt/decrypt the header in a secured document. This will ensure thatthe newly generated user key is usable when available in a clientdevice. According to another embodiment, a pair of keys associated witha user is updated. Since the two keys are retained in the server andnever leave the server, any appropriate cipher may be applicable for useto update the user keys.

Depending on the actual situation and an implementation in which theuser key(s) is being replaced, the newly generated key(s) may be keptwith the key manager or released to a client machine next time acorresponding user logs on therefrom. At 518, the process 510 awaits adecision whether the newly generated keys remain with the server or isdownloadable to a client. When the decision is to retain the newlygenerated key(s) in the server, the process 510 goes to 522 in which thenew key are set to be associated with the same user. When the decisionis to release the newly generated keys to the user next time the userlogs onto the server, the process 510 goes to 522. At 522, the process510 awaits a contact from the user. As described above, the user maylogin on any time from a client machine when he/she needs to access asecured document. When such contact does happen, the server will receivethe credential information from the user to ensure that the user is whohe/she claims to be. After the user is authenticated, the new keys areencrypted with the credential information at 524. The credentialinformation is provided by the user when requesting for authenticationand may include a set of username and password or a biometric feature(e.g., a fingerprint) of the user. Regardless of what cipher is used,the newly generated keys are converted into an illegible format at 524.The encrypted new keys are then uploaded or transmitted to the clientmachine at 526. Upon receiving the encrypted new keys, the clientmachine is caused at 528 to decrypt the encrypted new keys to make thenew user keys readily available for accessing secured documents orsecuring documents. In some cases, the client module in the clientmachine may be scheduled to scan in designated folders all availablesecured documents whose headers were originally encrypted by the olduser key. These documents can be now encrypted again with the new key toensure that the secured documents are indeed secured. In a preferableembodiment, the updating of user keys can be made to performtransparently as far as the users are concerned. In other words, theusers are not aware that the process 510 has happened and the new keysare now installed.

Referring now to FIG. 5B.4, there is shown a flowchart of a serverassisted process 530 of accessing secured documents according to oneembodiment of the present invention. The process 530 is discussed belowwith reference to FIG. 3. One of the features in the process 530, aswill be further described below, is that a user key or user keys (i.e.,a private and a public key) never leave the server where the keys aregenerated, which may enhance the level of security to the keys.

It is assumed that a user attempts to access secured documents from aclient machine and has been authenticated by a server (e.g., server 500)running the access control management. When a secured document isselected, document securing module (DSM) 302 of FIG. 3 determines that auser key is required to access the security information in the secureddocument. According to this embodiment, the DSM 302 is configured toseparate the header from the secured document and then send the headerto the server. At 532, such header is received from the client machine.As described before, the header includes security information in anencrypted form. At 534, a private user key associated with the user isretrieved. The private user key can, for example, be retrieved from thekey manager. The encrypted security information in the header is thendecrypted with the retrieved private user key at 536. As a result, theaccess rules for this secured document are obtained at 538.

At the same time, the access privilege for the user is retrieved at 540.The access privilege can, for example, be retrieved from the accountmanager. With the given access privilege and the access rules of thedocument, an evaluation takes place at 542 to determine if an accessright can be granted. If the user's access privilege does not permitaccess according to the access rules, the process 530 goes to 544. At544, an error message may be generated to forward to the client machineso that the user knows his access privilege does not allow him to accessthe selected document. However, on the other hand, if the user's accessprivilege does permit access according to the access rules, the process530 goes to 546. At 546, the file key in the security information can beretrieved. At 548, the file key is forwarded to the client machine. Withthe received file key, the DSM 302 activates the cipher module 310 todecrypt the encrypted data portion of the selected document.

FIG. 5B.5 shows a flowchart of a server assisted process 550 of securinga document according to one embodiment of the present invention. Theprocess 550 is discussed below with reference to FIG. 3. It is assumedthat a user has just finished a document and decided to secure thedocument. One possible way to secure the document, as described above,is to place it in a designated folder that is preset for or associatedwith a set of access rules. In other words, all documents in the foldermay have substantially similar access rules.

Accordingly, the DSM 302 is activated and in return also activates thecipher module 310. If the document is being secured for the first time,the cipher module 310 will generate a new file key. If the file isalready in existence, typically the cipher module 310 will not generatea new file key unless requested to do so. Before the process 550 starts,it is also assumed that the user has been authenticated and a linkbetween the client machine and the server is established.

Upon receiving the file key at 552 from the client machine, a publicuser key associated with the user is retrieved, for example, from thekey manager at 554. The access rules for the document are obtained at556. As described above, there are a number of ways to obtain the accessrules. One possible way is to receive them directly from the clientmachine. Another possible way is to get from the rules manager locallyif the document is placed in a folder setup by the system. Given theaccess rules and the file key, it is now possible to form the securityinformation at 558. The security information is then encrypted with thepublic user key at 560. In one embodiment similar to FIG. 2C.2, theaccess rules and the file key are placed in a segment if there are othersegments already in the rules block.

At 562, the header for the document is generated. Depending onimplementation, the header may include other information (e.g., a flag)that is not encrypted. Alternatively, a user block including the currentuser is also added into the header. The header is then forwarded at 564to the client machine where the header is attached or integrated withthe encrypted data portion to produce a secured document. It should benoted that the process 550 is also applicable when a secured document isbeing revised and saved into a store.

FIG. 5C shows a functional block diagram of a local server device 570.The local server device 570 is generally similar to that of a server asillustrated in FIG. 5A. Accordingly, many parts illustrated in FIG. 5Care not to be described again to avoid obscuring aspects of the presentinvention. As shown in FIG. 5C, the local server device 570 alsoexecutes a module, referred herein as a local module 572 which isconfigured to be a complete or partial replication of the server module502 of FIG. 5A. As one of the features in the present invention, thelocal module 572 provides the dependability, reliability and scalabilityof the centralized access control management being undertaken by thecentral server 500 of FIG. 5A. As such, not all authentication requestsneed to be handled at one central point without losing control of theaccess control management. As another feature of the present invention,the users are not affected if the central server is brought down formaintenance and the connection to the central server is not available.If a number of local servers are used and each has a replication of theserver module, the reliability of servicing the users is greatlyenhanced. The possibility that a user wants to access a secured documentbut could not be authenticated is minimized.

According to one embodiment, the local module 572 is a localized versionof some of the server module 502 in the central server 500 and servicesthe users local to the local server. For example, in FIG. 5D, it shows atable 584 of all the users managed by the central server 500. Among theusers, John's access privilege 585 is at level 10 (assumed highest) andcan access secured documents all days at all times from any of the threelocations. Dell's access privilege 586 is at level I (assumed lowest)and can access secured documents 8 hours (e.g., 9:00 AM-5 PM) a day,Monday to Friday and only from location A. Mike's access privilege 587is at level 5 and can access secured documents 12 hours Monday toSaturday and only from locations A and B. If three local servers areemployed respectively for the three locations A, B and C, there can bethree different access control management possibilities as shown in FIG.5E, each assigned to one local server. As a result, the local users needonly to check with the corresponding local server and none of the userswould be affected if other local servers are down for whatever reasonsor disconnected from the central server.

FIG. 5F illustrates the accessibility for each of the users. Workingwith the user monitor 512 in the server module 500, the local module 572can be configured dynamically. In one embodiment, instead of havingthree local modules, each permitting John to access from any of thethree locations, only one local module is configured to permit John toaccess form one of the three locations at one time. One of theadvantages of the additional security this dynamic configurationmechanism provides is that secured documents can be accessed by Johnfrom only one location at a time. In fact, it is not a desirablesecurity feature for a person to log into a system or to access secureddocuments from two physical locations at the same time. Also forsecurity reasons, it is preferably that a user, regardless of his/heraccess privilege, be permitted only a single access location at alltimes.

FIG. 5G shows a dynamic configuration affecting access controlmanagement. At one time, the system knows that John is accessing fromlocation A. When John moves to location B, upon his login, the centralserver (i.e., the user monitor in the server module) detects hiswhereabouts and thus notifies the local server manager 514 toreconfigure the local modules for both location A and location B. Asshown in FIG. 5G, the local access control management 589 in a localserver for location A is no longer responsible for John, while the localaccess control management 590 in a local server for location B takesover to be responsible for John. As a result, John is now permitted toaccess secured documents from location B but no longer from location A.FIG. 5H illustrates graphically that now John's accessibility has movedfrom location A to location B. Hence, John together with Mike, both canaccess secured documents from location B and both of them aretemporarily not permitted to access documents from location A.

If Mike happens to move to location A, again the local modules will bereconfigured as shown in FIG. 5I Because of John's access privilege,John can access secured documents from location C if he moves thereto.

FIG. 6A shows a flowchart of a user authentication process 600 that maybe implemented in the central server 500 or the local server 570. Asdescribed above, there are at least two situations that will call uponthe process 600—initial login to a networked client machine and firstaccess to a secured document. When either of these situations happens, aclient module in the client machine initiates a request that istransmitted to a server running a module providing the access controlmanagement to start the process 600.

At 602, the server awaits the request. Upon receiving the request fromthe client machine, the server proceeds at 604 to determine if the userand the client machine from which the user attempts to access a secureddocument have been authenticated. If both have already beenauthenticated, there will be no more authentication processing foreither of the user or the client machine. On the other hand, theauthentication processing continues when the user and the client machinehave not already been authenticated. In one embodiment, the server mayinitiate a secured link with the client machine if both the server andthe client machine are coupled to an open network, such link may be overHTTPS or supported through VPN. Alternatively, there may be a directlink between the client and the server if another authentication meansis employed.

At 606, the server responds to the received request with anauthentication response. Depending on implementation, such response maybe a dialog box to be displayed on the screen of the client machine, acommand or other demand. In any case, the response requires thatcredential information be provided by the user. As described before, thecredential information may be a set of username and password orbiometric information of the user and must be received from the user at608 before the authentication may proceed forward.

At 610, upon receiving the credential information, the server needs todetermine if the user is an authorized one to access any secureddocuments maintained in a repository, a local store, the server itselfor other device accessible over the network. This may involve in a matchof the received credential with what is previously stored in the server.It should be noted that the server may be the central server or a localserver. Those skilled in the art can understand that the description isequally applied in either one of the settings. If the match fails,namely the user is unauthorized, the process 600 goes back to thebeginning to continue waiting for a request. In other words, the currentrequest to access the secured documents or login to the system isabandoned. If the match successes, the user is recognized as beingauthorized.

At the same time, the client machine goes to a similar authenticationby, perhaps, an IP address thereof, or a network card identificationtherein, or other means that uniquely identifies the client machine.

With authentication of both the user and the client machine, the process600 goes to 612 where the user's access privilege is retrieved andactivated. Depending on implementation, an activation of the user'saccess privilege may be a downloading of a file containing the accessprivilege to the client machine, a decryption of a local file containingthe access privilege, or simply an activation of the user in a memoryspace of the server. In any case, at this point, the user's accessprivilege is readily accessible, thus permitting the user to access thesecured documents from the authenticated client machine.

According to one embodiment, XML-RPC is used to facilitate thecommunication between a server (e.g., a local server or a centralserver) and a client machine. XML-RPC is a simple and portable way tomake remote procedure calls over HTTP. It can be used with Perl, Java,Python, C, C++, PHP and many other programming languages. In addition,XML-RPC allows software running on disparate operating systems, runningin different environments to make procedure calls over a data network.It is remote procedure calling using HTTP as the transport and XML asthe encoding. XML-RPC is designed to be as simple as possible, whileallowing complex data structures to be transmitted, processed andreturned.

In the embodiment of implementing the dynamic configuration mechanism,the user contacts the server from a client machine, the local module inthe local server is examined to determine if it has authorization toservice the user from the client machine at this location. If not, thelocal server will communicate with the central server to determine ifthe local module shall be reconfigured or updated to subsequentlysupport the user from the client machine at this location. With thereconfigured local module, the user and the client machine can beauthenticated and the user's access privilege is made accessible, thuspermitting the user to access secured documents from the authenticatedclient machine.

To continue the above embodiment employing one or more local servers tostore a localized version of the server module so as to provide onlylocalized access control management. FIG. 6B shows a flowchart ofdynamically configuring the access control management process 620 whichmay be implemented in one or more local servers. The process 620 isperformed 610 and 612 of FIG. 6A. At 610, the user has been determinedto be authenticated.

Next, at 622, the server needs to determine the number of locations orcomputers from which the user is authorized to access the secureddocument. In operation, the user's access privilege is examined.Typically, the user's access privilege includes information identifyingwhere (e.g., a permitted location, a geographic location or a local areanetwork) and/or which local computers the user can utilize (e.g.permitted computers). In some case, a user travels a lot among a fewoffices in several geographic locations, thus the user could beprivileged to access secured documents from either one of thesegeographic locations/computers.

At 624, the current location of the user from which the request isreceived is examined to determine if it is from the permitted locationsin the access privilege. When the current location is not among thepermitted locations, the process 620 goes to 626 which may send anotification to the user or simply denies the request. If the currentlocation is among the permitted locations, the process 620 goes to 628where the local module providing localized access control management atpresent time is examined (e.g., in the local server manager 514 of FIG.5A) to determine if the user is under the localized access controlmanagement thereof. If the user is under the localized access controlmanagement by the local module, the process 620 goes to 612 of FIG. 6A.If the user is not under the localized access control management by thelocal module, the server needs to determine at 630 which local modulepreviously provided localized access control management for the user.Once the information is gathered from the local modules of differentlocal servers, a reconfiguration of the local modules takes place at632. Essentially, the user support is removed from one local module andadded to another local module, which will be further described in FIG.6C.

At 634, the newly configured local modules are respectively uploaded tothe corresponding local servers. As a result, the user can accesssecured documents from the new location while the system is assured thatonly one location/computer access permit is granted at all times.

One of the features in the mechanism of dynamically reconfiguring localmodules is the dependability, reliability and scalability of the centralaccess control management by the central server 500 of FIG. 5A. When anenterprise has many employees in multiple locations, the local serverscan be added to accommodate the needs without compromising theperformance. In fact, the users are not much affected for apredetermined period if the respective connections between the centralserver and the local servers are not available.

FIG. 6C shows a flowchart of reconfiguring the local modules process 640according to one embodiment. The process 640 is, for example, processingperformed at 632 of FIG. 6B. At 642, a first local module thatpreviously supports the user at first location is identified. At 644,the first local module is reconfigured to essentially remove support tothe user at the first location. The newly configured first local moduleis then uploaded at 646 to the corresponding local server to beeffective, such that the user is no longer supported at that localserver. At 648, a second local module that is to support the user at 2ndlocation (i.e., currently where the user is) is identified. At 650, the2nd local module is reconfigured to essentially add the support to theuser at the 2nd location. The newly configured second local module isthen uploaded at 652 to the corresponding local server to be effectiveas such the user is now supported at the local server.

The configuration of a user's access to secured document is sometimesreferred to as a provisioning process. The dynamic provisioning that hasbeen described above is believed to provide the necessary security meansneeded by a large enterprise having employees in several locationswithout the loss of the centralized access control management at acentral server. Further, the use of multiple local servers to supportthe central server can provide increased dependability, reliability andscalability.

Referring now to FIG. 7A, there is shown a functional block diagram of aclient machine 700. As used herein, the client machine 700 is acomputing device primarily used by a user to access secured documents.The client machine 700 can, for example, be a desktop computer, a mobiledevice or a laptop computer. According to one embodiment, the clientmachine 700 includes a processor 701, a client module 702, a memoryspace 703, a network interface 705 and a local store 707. The clientmodule 702 resides in the memory space 703 and, when executed by theprocessor 701, delivers features, advantages and benefits contemplatedin the present invention. Through the network interface 705, the clientmachine 700 is capable of communicating over a data network with othercomputers, such as a server. From the client machine 700, a user canaccess secured documents located in a repository (store) 706 that may bein the client machine 700, another networked device, or other storagemeans. A client module 702 is an executable version of one embodiment ofthe present invention. According to one embodiment, the client module702 includes a number of sub-modules including an access report module704, a user verifying module 710, a key manager 708, a document securingmodule 711 and an off-line access manager 714.

Access Report Module 704:

This module is a software agent configured to record access activity andassociated with an authenticated user. It reports to an access reportmodule in the central server so that a record may be established as towhat secured document has been accessed by which user during what time.In particular, the access report module 704 is activated to captureaccess activities of the user when the client machine is not networked.The access activities will be later synchronized with the counterpart inthe server to facilitate the access control management for the offlineaccess.

Key Manager 708:

One of the purposes for the key manager 708 is to ensure that a secureddocument is still usable when the secured document is being accessed byan application that suddenly crashes. According to one embodiment, afterthe encrypted header is decrypted, the file key is then copied or a copythereof is stored (cached) into the key manager 708. The file key isthen used to decrypt the encrypted document. A clear document is nowavailable to the application. If the application crashes due to poweroutage or interfered by another application or OS, the file key in theheader could be damaged. If no copy of the file key is available, thesecured document may not be usable any more because the encrypteddocument would not be decrypted without the file key. In this case, thereserved key maintained in the key manger can be used to replace thedamaged key and decrypt the encrypted document. After the user saves thefile again, the file key is put back into the header. Another purposefor the key manager 708 is to cache a user key or keys of anauthenticated user.

User Verifying Module 710:

This module is responsible for determining if a user who is accessing asecured document has been authenticated otherwise it will initiate arequest for authentication with a local server or a central server. Inother words, the user verifying module 710 is always consulted before apermission is granted to the user seeking access to a secured document.According to one embodiment, a user key or keys of an authenticated userare stored (cached) in the key manager 708 once the user isauthenticated by the user verifying module 710 via the server. When asecured document is accessed, the user key must be retrieved from thekey manager 708 to decrypt the encrypted security information in theheader of the secured document.

Document Securing Module 711:

As described above, the DSM 711 includes a cipher 712 that is used togenerate a file/user key and encrypt/decrypt a document/header. Inaddition, other securing means may be implemented in the DSM 711, forexample, a filter to block copying contents in a secured document into anon-secured document or a link from a secured document/original sourceto another document or recipient source.

Off-Line Access Manager 714:

This module becomes effective only when the networked client machine isoff the network, namely, the communication with a local server or acentral server is not currently available. For example, a user is on theroad and still needs to access some secured documents in a laptopcomputer. When live consultation is not available, the off-line accessmanager 714 is activated to ensure that the authorized user still canaccess the secured document but only for a limited time and perhaps witha limited privilege.

It should be pointed out that the client module 702 in FIG. 7A listssome exemplary sub-modules according to one embodiment of the presentinvention and not every module in the server module 702 has to beimplemented in order to practice the present invention. Those skilled inthe art can understand that given the description herein, variouscombinations of the sub-modules, may achieve certain functions, benefitsand advantages contemplated in the present invention.

Many aspects of the operations of the client module 702 have beendescribed above. The client module 702 can provide off-line accesscapability to a user to permit working with a secured document remotelywith respect to a server (i.e., the central server or a local server).The dependence on the server (either one of the central server or localserver) is so minimal that the feature can be equally applied to mobileusers. Referring now to FIG. 7B, there is shown a flowchart of providingthe off-line access process 720 in accordance with one embodiment of thepresent invention.

When a user has decided to be away from a company's premises for acertain period and will need to access some secured documents in aclient machine (e.g., a laptop computer) that is to be carried with theuser, the user may get preauthorization from the server before the userdisconnects the client machine from the network. At 722, thepreauthorization request is made in the client machine to seek anapproval of an off-line access request from a server (e.g., a centralserver or a local server). Depending on an exact implementation, aresponse to the preauthorization request received from the server may bea dialog box requesting further information from the user for the serverto proceed with the off-line access request.

At 724, the user enters necessary information to the off-line accessrequest that may include a specific time period, the user's identity.Perhaps, the off-line access request may also include the names of thesecured documents or directories/folders in which secured documents arelocated and will be accessed off-line. In general, the specific time ismanually entered or selected while the user's identity is automaticallyentered since the user typically has been previously authenticated andthe client machine has the user's identity. The off-line access requestis then forwarded to the server where the off-line access request isprocessed. It is assumed that the user is authorized to have suchoff-line access privilege.

In operation, there are a number of possible ways to enable the off-lineaccess capability. One exemplary way is to place a time-sensitive accessamendment to the desired secured documents, for example, the user ispre-authenticated by granting a pair of newly generated short-lived userkeys or uploading the user's key or keys in illegible format to theclient machine (only the private key is needed if only to access secureddocuments and both are needed if also to secure newly createddocuments). In other words, the user's access privilege or the accessrules in the selected secured documents have been updated for therequested period. Accordingly, depending on implementation, the amendedaccess rules, the amended access privilege or a time-sensitive userkey(s) is received from the server at 726.

At 728, the original access rules or the user's original accessprivilege or the original user key(s) is modified, updated ortemporarily overwritten. When the amended access rules are received, thesecured documents are processed to include the amendments in the accessrules so that the user can access them later even when off-line. Whenthe amended access privilege is received, the user's original accessprivilege is temporarily revised with the received amendments so thatthe user can now access secured documents off-line. When thetime-sensitive user keys are received, the user's original keys aresuspended (e.g. put into an illegible format and they are no longerreadily usable) and the newly received keys will be effective during theoff-line access period. FIG. 7C illustrates that an amendment of theaccess rules is placed into a secured document that can be accessed byUsers, A, B, C and D, wherein User A has requested for the off-lineaccess and has been granted off-line access for the request, while UsersB, C and D cannot access the secured documents off-line.

For security purposes, the amendment will typically expire by the end ofthe specific off-line time regardless if the user has returned or not.This feature is important to the situations in which the client machine(e.g. a laptop computer) is separated from the user or possessed by anunauthorized person, because the secured documents in the client machinecan be no longer accessed with the expired user keys even if the user'sconfidential information (username/password) is hacked. Therefore, at730, the process 720 keeps checking if the off-line time has ended. Ifnot, the user can still access the secured documents off-line. When itis detected that the off-line time has expired, the process 720 goes to734 wherein the original access rules are restored so that the secureddocuments can no longer be accessed off-line.

Similarly, the user's amended access privilege may be configured toexpire as well when it is detected that the off-line time is expired,the process 720 goes to 734 wherein the user's original access privilegeis restored so that the secured documents can no longer be accessedoff-line. According to one embodiment, the amended access privilege isoverwritten by the original access privilege.

To account for the situation in which the user may cut short of his/hertravel, the process 720 may be configured to initiate the restoration ofthe original setting for the secured documents or the user's accessprivilege. At 732, the client machine detects that a connection to aaccess control server has been made; hence, it is assumed that theoff-line access is no longer needed. The process 720 goes to 734 wherethe restoration of the original setting for the secured documents, theuser's access privilege or user's keys takes place. As a result, thesecured documents can no longer be accessed off-line from the clientmachine.

In any case, it is preferable to invoke the access report module 704 inthe client module 702 to record the access activities by the user duringthe off-line access. The next time the user connects to the server, theaccess activities of the secured documents can be reported to the serverto facilitate the access control management or synchronization of thesecured documents accessed during the off-line period.

There are numerous functions, benefits, and advantages in the presentinvention. One of the functions, benefits and advantages is that thesecuring mechanism contemplated in the present invention keep selecteddigital assets under protection at all times by employing access rulesin the secured digital assets. As such only authorized user withauthenticated machines can access the secured digital assets. Otherfunctions, benefits, and advantages are apparent to those skilled in theart given the detailed description herein.

The present invention may be implemented as a method, a system, acomputer readable medium, a computer product and other forms thatachieve what is desired herein. Those skilled in the art will understandthat the description could be equally applied to or used in othervarious different settings with respect to various combinations,embodiments or settings provided in the description herein.

The processes, sequences or steps and features discussed above arerelated to each other and each is believed independently novel in theart. The disclosed processes, sequences or steps and features may beperformed alone or in any combination to provide a novel and unobvioussystem or a portion of a system. It should be understood that theprocesses, sequences or steps and features in combination yield anequally independently novel combination as well, even if combined intheir broadest sense, i.e., with less than the specific manner in whicheach of the processes, sequences or steps and features has been reducedto practice.

The forgoing description of embodiments is illustrative of variousaspects/embodiments of the present invention. Various modifications tothe present invention can be made to the preferred embodiments by thoseskilled in the art without departing from the true spirit and scope ofthe invention as defined by the appended claims. Accordingly, the scopeof the present invention is defined by the appended claims rather thanthe foregoing description of embodiments.

What is claimed is:
 1. A central server for providing access control tosecured data, comprising: a memory coupled to at least one hardwareprocessor, the at least one hardware processor configured to:authenticate a mobile device in response to a file access requestreceived from the mobile device at a first local server, wherein themobile device is associated with a user, and wherein the authenticationis based on an identifier of the mobile device; determine whether thefirst local server is configured to provide localized access control forthe user; and in response to determining that the first local server isnot configured to provide localized access control for the user:reconfigure the first local server to provide localized access controlfor the user by identifying a location of the authenticated mobiledevice from which the file access request originates so as to permitaccess by the user from a single access location at a time; identify asecond local server that previously provided localized access controlfor the user; and remove localized access control support for the userfrom the second local server.
 2. The central server of claim 1, whereinto reconfigure the first local server, the at least one hardwareprocessor is further configured to: retrieve a first local module of thefirst local server; reconfigure the first local module to add supportfor the user at the location of the mobile device; and upload thereconfigured first local module to the first local server.
 3. Thecentral server of claim 1, wherein to remove localized access controlsupport for the user, the at least one hardware processor is furtherconfigured to: retrieve a second local module of the second localserver; retrieve a location associated with the user from the secondlocal module; reconfigure the second local module to remove support forthe user at the identified location associated with the user; and uploadthe reconfigured second local module to the second local server.
 4. Thecentral server of claim 1, wherein the user is a human, a group of humanusers, an application, a process, a software agent, a group of softwareagents, a software application, a database query, devices, or executingcomputer processes that submit or spawn requests for electronic data andcan be associated with a user key.
 5. The central server of claim 1,wherein the at least one processor is further configured to authenticatethe mobile device in response to the file access request received at thefirst local server.
 6. The central server of claim 5, wherein theauthentication of the mobile device is based on biometric informationprovided by the user associated with the mobile device.
 7. The centralserver of claim 1, wherein the central server is coupled to the firstlocal server via an enterprise network, and wherein the first localserver is configured to: identify a secured file from the file accessrequest; retrieve an access rule corresponding to the secured file;retrieve an access privilege of the user associated with the mobiledevice; determine whether to permit the mobile device to access thesecured file based on the access rule and the access privilege of theuser; and transmit the secured file and a file key to the mobile devicein response to determining to permit the mobile device to access thesecured file, the file key enabling access to the secured file.
 8. Amethod for providing access control to secured data, comprising:authenticating a mobile device in response to a file access requestreceived from the mobile device at a first local server, wherein themobile device is associated with a user, and wherein the authenticationis based on an identifier of the mobile device; determining whether thefirst local server is configured to provide localized access control forthe user; and in response to determining that the first local server isnot configured to provide localized access control for the user:reconfiguring the first local server to provide localized access controlfor the user by identifying a location of the authenticated mobiledevice from which the file access request originates so as to permitaccess by the user from a single access location at a time; identifyinga second local server that previously provided localized access controlfor the user; and removing localized access control support for the userfrom the second local server.
 9. The method of claim 8, wherein thereconfiguring further comprises: retrieving a local module of the firstlocal server; reconfiguring the local module to add support for the userat the location of the mobile device; and uploading the reconfiguredlocal module to the first local server.
 10. The method of claim 8,wherein the removing further comprises: retrieving a second local moduleof the second local server; identifying retrieving a location associatedwith the user from the second local module; reconfiguring the secondlocal module to remove support for the user at the identified locationassociated with the user; and uploading the reconfigured second localmodule to the second local server.
 11. The method of claim 8, whereinthe user is a human, a group of human users, an application, a process,a software agent, a group of software agents, a software application, adatabase query, devices, or executing computer processes that submit orspawn requests for electronic data and can be associated with a userkey.
 12. The method of claim 8, further comprising authenticating themobile device in response to the file access request received at thefirst local server.
 13. The method of claim 12, wherein theauthentication of the mobile device is based on biometric informationprovided by the user associated with the mobile device.
 14. The methodof claim 8, further comprising: identifying a secured file from the fileaccess request; retrieving an access rule corresponding to the securedfile; retrieving an access privilege of the user associated with themobile device; determining whether to permit the mobile device to accessthe secured file based on the access rule and the access privilege ofthe user; and transmitting the secured file and a file key to the mobiledevice in response to determining to permit the mobile device to accessthe secured file, the file key enabling access to the secured file. 15.The method of claim 8, wherein the first local server and the secondlocal server are part of a private enterprise network.
 16. Anon-transitory computer-readable storage device having instructionsstored thereon that, when executed by at least one computing device,causes the at least one computing device to perform operationscomprising: authenticating a mobile device in response to a file accessrequest received from the mobile device at a first local server, whereinthe mobile device is associated with a user, and wherein theauthentication is based on an identifier of the mobile device;determining whether the first local server is configured to providelocalized access control for the user; and in response to determiningthat the first local server is not configured to provide localizedaccess control for the user: reconfiguring the first local server toprovide localized access control for the user by identifying a locationof the authenticated mobile device from which the file access requestoriginates so as to permit access by the user from a single accesslocation at a time; identifying a second local server that previouslyprovided localized access control for the user; and removing localizedaccess control support for the user from the second local server. 17.The non-transitory computer-readable storage device of claim 16, whereinto reconfigure the first local server, the operations further comprise:retrieving a local module of the first local server; reconfiguring thelocal module to add support for the user at the location of the mobiledevice; and uploading the reconfigured local module to the first localserver.
 18. The non-transitory computer-readable storage device of claim16, wherein to remove localized access control support for the user, theoperations further comprise: retrieving a second local module of thesecond local server; retrieving a location associated with the user fromthe second local module; reconfiguring the second local module to removesupport for the user at the identified location associated with theuser; and uploading the reconfigured second local module to the secondlocal server.
 19. The non-transitory computer-readable storage device ofclaim 16, wherein the user is a human, a group of human users, anapplication, a process, a software agent, a group of software agents, asoftware application, a database query, devices, or executing computerprocesses that submit or spawn requests for electronic data and can beassociated with a user key.
 20. The non-transitory computer-readablestorage device of claim 16, the operations further comprising:identifying a secured file from the file access request; retrieving anaccess rule corresponding to the secured file; retrieving an accessprivilege of the user associated with the mobile device; determiningwhether to permit the mobile device to access the secured file based onthe access rule and the access privilege of the user; and transmittingthe secured file and a file key to the mobile device in response todetermining to permit the mobile device to access the secured file, thefile key enabling access to the secured file.